Moisture measurement method using a Karl Fischer reagent

摘要

PURPOSE:To measure the moisture content in a sample with an instrument which is simple and is easy to maintain irrespectively of the change in the strength of the reagent with age by bringing a specified amt. of a sample into reaction with a specified amt. of a Karl Fischer reagent and measuring the absorption quantity of light before and after the reaction. CONSTITUTION:Dehydrated methanol as a solvent and the Karl Fischer reagent are put into a glass container 1 and are uniformly stirred. A sensor for measuring absorbancy having an optical fiber 8 is put into the liquid and the absorbancy based on the iodine in the reagent is measured. A water-methanol soln. having a known moisture content is then put into the container and the absorbancy is measured. The constant (k) of the equation I is calculated. The moisture content in the sample is calculated from the equation I if the sample of an unknown moisture concn. is put into the container and the absorbancy thereof is measured. IN the equation, S: the amt. of the sample introduced, M: the amt. of the solvent introduced, K: the amt. of the Karl Fischer reagent introduced (all said amts. are in ml), A1: the absorbancy before the sample introduction, A2: the absorbancy after the sample introduction, (k): a constant.